In most types of electronic devices, there are one or more circuit boards that have integrated circuits mounted on them. Examples of integrated circuits include processors, such as central-processing units (CPUs), as well as other types of integrated circuits. Integrated circuits can emit an extraordinary amount of heat during their operation. If this heat is not moved away and expelled from the integrated circuits, the integrated circuits can fail.
Therefore, for integrated circuits that generate sufficient heat, components known as heat sinks are attached to the circuit board so that they come into contact with the integrated circuits. Heat from an integrated circuit is transferred to a heat sink, which dissipates the heat away from the integrated circuit. Heat sinks may be passive or active. Passive heat sinks typically include a number of highly heat conductive fins, whereas active heat sinks typically include fans.